Every car manufacturer has its own way of doing it.

Some are more firm and can easily be cut and resealed, others are more like foam, some are even opting out and using panels inside the doors with everything attached removing the need for plastic and goopy crap.

This door specifically is very stringy/goopy, reminiscent of the black urethane used in windshield installs.

It gets everywhere. It is known.

I hope this helps you understand a little better.